Electron discharge assembly



Jun 23, 1959 c. L. DAY 2,892,087

, 2 Sheets-Sheet 1 4 5 e '3 IO as 31 I 2 as I a I INVENTOR.

4 .CYRIL L. DAY 00000004 ATTORNEY c. L. DAY

ELECTRON DISCHARGE ASSEMBLY June 23, 1959 Filed Jim 14. 1956 2 Sheets-Sheet 2 INVENTOR. CYRIL L. DAY

M a rronnsr United States Patent fiice 2,892,087 ELECTRON DISCHARGE ASSEMBLY Cyril L. Day, Huntington, Ind.,;assignor to International Telephone and Telegraph Corporation Application June 14, 1956, Serial No. 591,424 8 Claims. Cl. 250-495 The present invention relates to an electron discharge assembly, and more particularly to a camera adapted to expose photographic film directly to electron radiation.

Image tubes of the type disclosed in Day Patent No. 2,708,250, Morton et al. Patent No. 2,487,665 and Flory et al. Patent No. 2,506,018 respectively include a photoelectric cathode, a phosphor screen anode, and suitable electron-accelerating electrodes for projecting an electron image from the cathode onto the anode. In conventional operation, a radiation image, such as an infra-red image,,:is focused onto the cathode which, in response thereto, emits a corresponding electron image. This electron image is then electron-optically projected onto the phosphor screen which is thereupon excited into luminescence for reproducing visibly the electron image. This particular image tube is well known in the art and is contained in many different configurations'adapted for difierent purposes. As will appear from the following, this invention is not limited to a particular image tube construction, but instead is adapted for use with any electron discharge device wherein electrons are projected into or onto a particular region or plane.

In general, this invention comprehends replacing the phosphor screen with a sheet of photographic film which is exposed directly to the electron image. By means of this replacement, the amplification factor of the image tube is markedly increased so that the. tube may be utilized with lower intensity incident radiation than would be possible with the use of a phosphor screen. Such an image tube finds its utility in devices such as electron telescopes and microscopes in which it is desired photographically to record the image magnified by the device; thisv invention thus eliminates the necessity of converting the electron image to an optical image for photographic reproduction, the electron image being directly exposed to the photographic film.

-It is therefore an object of this invention to provide an electron discharge device having a high amplification factor.

It is another object of this invention to provide a device for exposing photographic film directly to electron radiation. It is still another object of this invention to provide a camera for exposing successively a plurality of photographic films to electron radiation emanating from a single cathode structure. As a corollary, it is an object to provide a camera construction which utilizes a photoelectric cathode in such a manner that the same cathode may be used repeatedly for exposing different sheets or pieces of photographic film.

In the accomplishment of this invention, there is provided an electron discharge device comprising a first evacuated envelope, electron controlling elements in this envelope, and a second evacuated envelope enclosing at least a portion of the first envelope, this second envelope being adapted to be opened for admitting a sheet of photographic film.

The above-mentioned and other features and objects of 2,892,081 Patented June 23, 1959- I inserted in a camera unit;

Fig. 3 is a plan view of the cutter bar of the camera. of Fig. 2;

Fig. 4 is an enlarged fragmentary illustration taken substantially along section line 4-4 of Fig. 2;

Fig. 5 is an enlarged fragmentary illustration taken substantially along section line 5-5 of Fig. 2; and

Fig. 6 is a partial cross-sectional view of another embodiment of an electron discharge tube which may be used in this invention.

Referring to the drawings, and more particularly to Fig. 1, an image tube is shown which comprises a first evacuated envelope 1 having the usual internal electrodes such as the photoelectric cathode 2, and the electronoptical electrodes 3. In the end of the envelope 1 cpposite the cathode 2 is located the usual supporting plate 4 which ordinarily carries a film of phosphor material which luminesces in response to electron bombardment. However, in the present instance no phosphor film is used, but instead the plate 4, which is preferably fabri-' cated of metal, is slotted at 5, which slot is covered with an aluminum foil or film 6 from of 300 to 500 Angstroms thick. As will become more apparent from the following, this aluminum foil 6 is electron permeable. Encircling the supporting plate 4 is a ring structure 7 which projects beyond the surface of the foil 6 as shown for a purpose which will be explained more fully hereinafter.

A second evacuated envelope 7 surrounds the end portion of the first envelope 1 in the manner shown. This envelope 7 essentially includes a sleeve 8 which is her metically sealed to the envelope 1 and a removable closure plate 9 which normally bears against a stepped diameter ring 10 suitably alfixed, as by welding, to the inner wall of the sleeve 8. A Nichrome membrane 11 of approximately .002 thick is hermetically sealed over the plate 9 and flange 12 on the sleeve 8 for hermetically sealing the plate 9 to the sleeve 8. As seen in Fig. 1, an anunular space 13 separates the periphery of the closure plate 9 from the inner wall of the sleeve 8. The purpose of this space 13 will become apparent from the following description.

The finished tube of Fig. 1 is evacuated by conventional means to the usual pressures such as 10- millimeters of mercury. In other words, both of the envelopes 1 and 7,, are reduced in pressure to the value of 10- millimeters of mercury.

Referring now to Fig. 2, a camera housing 14 is composed essentially of two vacuum-tight chambers 15 and 16 which are selectively separable by means of a movable wall or partition 17. The chamber 15, which may be characterized as the tube-receiving chamber, is adapted to receive the tube of Fig. 1 in hermetically sealed relation, this seal being elfected by means of a radial flange; 18 on the tube which is clamped onto the end wall 19 by means of an annular clamp 20 which forces the flange 18 onto a conventional rubber O-ring seal 21. An exhaust connection 22 connects with the interior of the chamber 15, whereby the pressure therein may be reduced to a desired value. The chamber 16, which may be characterized as an operations chamber, for purposes which will become apparent from the following, is provided with a removable end plate 23 and an exhaust connection 24 for evacuating the chamber. The end plate 23 rotatably receives therethrough, in vacuum-tight relation, a shaft 24,, which carries a cutter bar 25 (see Fig. 3) having cutters or knives 26 on the opposite ends thereof and an internally'threaded hub 27'.

: nexternally threaded stud 28 on the closure plate 9 of the image tube is positioned for being threadedly received by the hub 27, as will be explained more fully hereinafter. i

- The partition 17 is movable into and out of chamberseparating relationship between the two chambers 15 and 16. This partition 17 bears against a shoulder 29 equipped with an ordinary rubber O-ring seal 30. The partition 17 is mounted on an operating rod 31 by means of two slotted lugs 32. "An eccentric cam 33 (Fig. is mounted on the rod 31 for rotation therewith and also for selective engagement with the partition 17. The lefthand end of the rod 31, as seen in Fig. 2, is received by asocket bearing 34 in the camera housing 14, the other end of the rod 31 passing through a suitable airtight bearing 35. An auxiliary or partition-receiving chamber 36 laterally extends from the camera housing 14 as shown and is of such depth as will receive completely the partition 17.

The partition is operated as follows. In the present illustrated position, the rod 31 is manually rotated to a point which causes the cam 33 to force the partition 17 against the O-ring seal 30 for providing a vacuum-tight seal or separation between the two chambers 15 and 16. The partition 17 is removed merely by rotating the rod 31 in such a direction as to withdraw the cam 33 from the partition 17, whereupon the latter is loosened. The rod 31, which is manipulated from the outside of the camera housing 14, is then longitudinally withdrawn for moving the partition 17 into the chamber 36. The chambers 15 and 16 are thereby fully opened to each other, providing a single large chamber.

Now considering the operation of the entire device thus far described, and assuming that the image tube is clamped into the camera chamber 15 as shown and already described, the partition 17 is operated to separate, in vacuum type relation, the two chambers 15 and 16. The two chambers 15 and 16 are thereupon evacuated to a suitably low pressure of, for example, to 10" millimeters of mercury. The partition 17 is now withdrawn into its chamber 36, thereby fully opening the two chambers and 16. The cutter 25, 26 is now operated by moving the shaft 24,, longitudinally inwardly until the hub 27 contacts the stud 28. The shaft 24,, is then rotated to thread the hub and stud together, rotation being continued until the cutters 26 slice through the Nichrome membrane 11 which bridges the annular space 13. By cutting this membrane 11, the closure plate 9 may simply be removed from the second evacuated envelope 7 by merely withdrawing the shaft 24,, until the entire assembly is positioned inside the chamber 16.

The partition 17 is next operated to seal off the two chambers 15 and 16. While maintaining the vacuum in chamber 15, atmospheric pressure is admitted to the chamber 16. The end plate 23 of chamber 16 is removed and the cutter 25 as well as the tube end-plate 9 are removed from the shaft 24.

A photographic film-supporting member or plate is next atfixed to the end of the shaft 24,, and a sheet of photographic film is placed on this supporting member (not shown). The chamber 16 is now closed by replacing the end plate 23 and shaft 24,, assembly, and the chamber 16 is once more evacuated. The partition 17 is once more retracted into the chamber 36, thereby permitting the shaft 24 to be longitudinally moved inwardly until the photographic film carried thereby is abutted against the spacer ring 7 surrounding the tube end plate 4.

.The cathode 2 of the image tube is thereupon exposed to radiation which causes electron emission. Such emission is thereupon projected into the plane of the end plate 4 as well as into the area of the slot 5, the electrons thereupon permeating the slot and the aluminum foil 6 to impinge and expose the photographic film. After exposure of the film, the film is merely retracted into the chamber 16. The partition 17 is replaced to separate the two chambers 15 and 16 and the end plate 23 is removed. The photographic film may thereupon be removed from the shaft 24,, assembly for development according to the usual techniques.

Recapitulating, it will now be understood that photoconstant in order to prevent the cathode from becoming contaminated and damaged. By means of this invention,"

photographic film exposures may be repeatedly effected without interfering with the vacuum in the tube. Thus,

the same image tube may be used over a long period; of time for producing a plurality of photographic film exposures. p

In manufacturing the image tube of this invention, the tube is equipped with the two evacuated envelopes 1 and 7 as previously explained. After the tube is inserted,

into the camera housing 14 and more particularly into the evacuated chamber 15, the evacuated envelope 7,, is broken or otherwise removed, thereby permitting a sheet of photographic film to be moved into contiguous regis-f try with the electron permeable slot 5.

Referring to Fig. 6, a slightly different type of tube construction is shown. The second evacuated envelope' in this instance comprises a glass cup or shell 37 which is circumferentially grooved or scored at 38 for receiving an annular section of high resistance heating wire (not shown). In operation, this tube of Fig. 6 is inserted in the camera housing 14 of Fig. 2 in the same manner as the tube therein illustrated, and the chamber 15 is evacuated as before. However, the evacuated en velope 37 is removed or broken away by passing a current through the Wire which lies in the groove 38, this current causing the wire to heat sufliciently to fracture and break away the glass shell. The end of the image.

tube is thereupon fully exposedfor receiving a sheet of photographic material in the manner previously described.

' While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention;

What is claimed is:

1. An electron discharge device comprising an evacuated envelope, electron-controlling elements in said envelope, a second evacuated envelope enclosing at least a portion of the first-mentioned envelope and attached thereto, and means for detaching a portion of said second envelope with the other portion remaining attached to said first envelope.

envelope including a removable closure element.

3. An electron discharge device comprising an evacuated envelope, electron-controlling elements in said en-. velope, a second evacuated envelope enclosing .at least a portion of the first-mentioned envelope, said second A envelope including a wall which surrounds at least a portion of said first envelope and a closure member for said wall which is hermetically sealed thereto, and remotely; controlled means for removingsaid closure member from said wall to open said second envelope.

4. An electron discharge device comprising an evacuated envelope, electron-controlling elements in said envelope, a second evacuated envelope enclosing at least a portion of the first-mentioned envelope, said second envelope including a sleeve which is hermetically sealed at one end to said first-mentioned envelope, a closure member hermetically sealed to the other end of said sleeve, and a remotely controlled device for removing said closure member from said sleeve.

5. An electron discharge device comprising an evacuated envelope, electron-controlling elements in said envelope, a second evacuated envelope enclosing at least a portion of the first-mentioned envelope, said second envelope including a sleeve which is hermetically sealed at one end to said first-mentioned envelope, a closure member covering the other end of said sleeve, a metallic membrane hermetically sealing said closure member to said sleeve, a membrane-cutting device operatively associted with said closure member, and an operating mechanism operatively connected to said cutting device for cutting said membrane.

6. An electron discharge device comprising an evacuated envelope, electron-controlling elements in said envelope, a second evacuated envelope enclosing at least a portion of the first-mentioned envelope, said second envelope comprising a glass shell, and means for breaking said glass shell away from said first-mentioned envelope.

7. In combination, an electron discharge tube comprising a first-evacuated envelope enclosing a plurality of electron-controlling elements, a second evacuated envelope enclosing one end portion of said first envelope, an airtight housing receiving said tube, said housing comprising a tube-receiving chamber and an operations chamber, a removable wall hermetically separating said chambers, and means extending from said housing for moving selectively said wall into and out of separating relation with said chambers.

8. In combination, an electron discharge tube comprising a first evacuated envelope enclosing a plurality of electron-controlling elements, a second evacuated envelope enclosing one end portion of said first envelope, an airtight housing receiving said tube, said housing comprising a tube-receiving chamber and an operations chamber, a removable wall hermetically separating said chambers, means extending from said housing for moving selectively said wall into and out of separating relation with said chambers, and means for producing selectively a partial vacuum in said chambers.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Electronic Photography of the Stars by Baum, vol. 194, #3, Scientific American, March 1956. 

